A kitchen machine of the kind mentioned in the opening paragraph is known from British Patent Application GB-2,082,713-A. In the known kitchen machine, the attachment is a blender jar and the tool is a blender knife which has its rotation bearings in a bottom portion of the blender jar. The blender jar can be placed on the motor housing, whereby the bottom portion of the blender jar can be locked on the motor housing and the blender knife can be coupled to the end of the drive shaft of the electric motor by means of a coupling bush, said motor being present in the motor housing and fastened to a motor frame. Instead of the blender jar with the blender knife, a transverse arm with a rotating beater may be placed on the motor housing, which beater can be coupled to the end of the drive shaft via a transmission provided in the transverse arm and a coupling bush. The beater in this case is positioned in a bowl which can be placed on a base of the kitchen machine next to the motor housing and rotated by the electric motor.
A disadvantage of the known kitchen machine is that the centerline of the drive shaft and the centerline of the coupling bush of the attachment are not in one line as a result of manufacturing tolerances. As a result, the application of the attachment on and the removal of the attachment from the motor housing may take place with difficulty, while friction losses may occur between the end of the drive shaft and the coupling bush during operation.